Calcium and Bones-- The Downfall of a Myth

Surprise! You can't count on calcium plus vitamin D supplements to prevent broken bones, says a major 7-year study of healthy women over age 50, funded by the National Institutes of Health.

In truth, it's not much of a surprise to many who research calcium. Despite the fact most doctors routinely push high doses of calcium as a magic bullet to save bones, especially for women reaching menopause, the evidence for it has always been flimsy and controversial.

Now, the results of this most comprehensive test of 36,282 normal healthy women over 50, make clear that gulping down lots of calcium is much less reliable insurance against broken bones that most women have been led to believe.   

In the study women were randomly assigned to take 1000 mg calcium and 400 IU vitamin D daily or a placebo. Here are the basic findings:

• Overall, hip bone density in women went up 1 percent, but this did not significantly reduce hip fractures. 
• However, in women over 60, the calcium and D did cut fractures 21%. 
• The supplements did not affect bone density or fractures in the spine, lower arm or wrist.
• Supplement takers had a 17% higher risk of kidney stones. 

Why was calcium so disappointing and what's a woman to do?

Expectations were way too high., and the study had drawbacks. The dose of vitamin D was probably too low. New research says at least 600 IU daily of vitamin D is needed to strenghten bones when combined with calcium. The women were atypically overweight; some were taking hormones, few were over 70, the age when fracture risk soars. Most were getting such high doses of calcium going into the study that maybe the extra didn't matter much. 

Most important, the study helps end a widespread myth--that calcium is a sure answer to osteoporosis and broken bones. It's much more complicated than that, says Katherine Tucker, leading bone researcher at Tufts. She points out that also important are B vitamins, magnesium, fruits and vegetables, restriction of colas, sugar and junk foods. Calcium is just one beneficial factor. And weight bearing exercise is another big one. 

Bottom Line: Experts still advise women, especially after age 60, to take calcium and vitamin D with the expectation of some bone benefits. But don't depend on it as a sure thing, and don't overload. A daily supplement of 500-800 mg of calcium is enough, along with at least 600 IU of vitamin D. 

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